This invention relates to safety wheels of the type including a tubeless tire and designed so that the bead portions of the tubeless tire are at all times firmly held in position on the rim on which the tire is mounted.
Generally, with wheels fitted with a tubeless tire, any dislocation of the bead portions of the tire may cause air leakage therefrom and, if the air pressure in the tire is reduced to any extreme extent as when the tire is punctured, the tire bead portions are liable to be disengaged from the rim, for example, during turning movement of the vehicle. Such disengagement of the tire bead portions will result in direct contact of the rim with the ground, and thus cause serious troubles such as side slip and reduction in braking efficiency, rendering the vehicle practically unable to travel any further. With such wheels, therefore, it is highly desirable that the tire bead portions, particularly of a tubeless tire, be at all times firmly held in position on the rim irrespective of the air pressure in the tire.
A tire bead holding means intended to meet this requirement has previously been known which includes a bead lock or stopper inserted in the tire to grip the bead portions between the stopper itself and the respective flanges of the rim, on which the tire is mounted, so that the tire bead portions may be held against any axial displacement and hence against disengagement from the rim. The known form of bead lock, however, has been rather poor in assemblability, incurring much trouble when assembled in the tire in a specified position, because of the fixed outer diameter of such bead lock, which is larger than the internal diameter of the tire. If not positioned properly in the tire, the bead lock can exhibit a reduced tire-holding capacity and may cause various troubles, including unbalance of the rotating mass and vibrations, which impair riding comfort of the vehicle.